My understanding is ICE can detain anyone they suspect of being an illegal alien. Have you ever been detained before? It feels an awful lot like being arrested, you even get placed in handcuffs.
Detaining someone and arresting someone basically look like the exact same action, they aren't though. Best thing to do is just shut your mouth, cooperate with the Officer's directions and not even try and argue about it. Arguing just makes the situation worse, you aren't going to win the argument anyways so there isn't even a point in trying to.
Proving that ICE officers targeted someone based on their race would basically be impossible. Not saying the optics aren't what they are, but optics and legal aren't the same thing.